This invention relates to generally to prosthesis for continuous internal peritoneal dialysis and a continuous method of carrying out peritoneal dialysis. More specifically, this invention relates to artificial kidneys, and more specifically to artificial kidneys implantable within a person""s body with the intent that the patient be free from dialysis and transplantation. The artificial kidneys of this invention employ the normal operation of the person""s body (i.e., breathing cycle of the person) to cause the flow of fluid within the prosthesis for the removal of toxic substances or other fluids from the person""s body. For the treatment of edema states that are refractory to treatment with diuretics the dialysate can be a selected hypertonic solution for removing excess fluids; principally water.
The dialysis art is a highly developed one; providing a variety of teachings for dialyzing a patient.
In accordance with a related dialysis procedure (e.g., hemodialysis) for purifying blood in a patient experiencing kidney failure, the contaminated blood is directed from a blood vessel of the patient""s arm through a dialyzing membrane located extracorporeally of the body, in which the blood gives up its impurities to the dialyzing fluid. The purified blood is then directed back into the patient""s body through another blood vessel. A representative disclosure of a system for use in purifying arterial blood and providing a venous return is disclosed in U.S. Pat. No. 3,579,441, issued to Brown.
The dialysis art also suggests the use of related peritoneal dialysis systems, wherein a dialysate is introduced directly into the abdomen of the patient and functions to receive impurities from the blood at the abdominal capillaries, and then is mechanically removed from the body. Representative peritoneal dialysis systems of this type are disclosed in U.S. Pat. Nos. 4,681,564 (Landreneau); 4,655,762 (Rogers); 4,586,920 (Peabody) and 4,437,856 (Valli).
All of the related art systems known to applicants suffer from one or more disadvantages. For example, a number of prior art systems require that the patient be connected, e.g., xe2x80x9chooked-upxe2x80x9d, to a dialysis machine. This renders the patient immobile during treatment, is expensive to administer, and subjects the patient to a high risk of infection, and even death. Patients are protein restricted, because protein yields toxic degradation products (e.g., nitrogenous wastes) largely responsible for uremia, the state of being in kidney failure. Toxic levels of potassium may also result from the treatment. Moreover, chronic contact of the peritoneum with hypertonic dialysate solutions often creates chronic peritonitis, which is a painful, dangerous condition that interferes with the peritoneal dialysis process.
The absorption of dialysate into the bloodstream interferes with the peritoneum dialysate""s ability to do its job of pulling in fluids. Therefore, peritoneal dialysis relies physiologically on the fact that the dialysis fluid in the abdominal cavity is more viscous or thicker than blood. In other words, the dialysis fluid has a higher osmolality or chemical potential than the bloodstream. This difference in potential causes water and other molecules known to those skilled in the art to diffuse into the abdomen via the semi-permeable membranes of the peritoneum and mesenteric parietes which line the abdominal cavity.
Additionally, all previous modes of dialysis have been essentially intermittent, rather than continuous; resulting in a variety of disturbances to the body""s equilibrium. Patients become either over-hydrated or under-hydrated due to the intermittent process of adding and removing fluids. The systems can not maintain proper blood volume and chemical balance beyond the few hours following the treatment. The treatments sap the patient""s energy and sense of well-being, making the patient look and feel chronically ill, and critically affecting the patient""s lifestyle, happiness and longevity.
With respect to transplantation, the high cost and risks are well known. A match for the patient must be found, which may take years. If a kidney is found, and the patient is still strong enough to receive it, then there is no guarantee that the kidney will be accepted. The patient""s immune system may recognize a kidney transplanted from another as foreign matter and act to combat and reject this perceived invasion. Anti-rejection medication, such as azathioprine, cyclosporine and steroids help to prevent rejection. However, anti-rejection medicines have a large number of side effects. If rejection occurs, treatment is available to possibly reverse the episode, but at the cost of more medication and side effects. With kidney transplantation, about one third of the patients do very well, about one third remain chronically ill, and about one third of the patients die within five years.
A need clearly exists for an artificial kidney, or prosthesis, that is lower in cost than existing systems, that can be utilized with a minimum of risk to the patient, that provides greater freedom of movement for the patient and that allows for the continuous formation of urine as in a normal functioning kidney. Therefore, it would be beneficial to provide a continuous internal peritoneal dialysis prosthesis and method. It would also be beneficial to provide a continuous internal peritoneal dialysis prosthesis and method which employs the normal breathing pattern of the patient to affect the dialysis operation, which is simple in operation and requires relatively few moving parts.
To applicant""s knowledge, prior to this invention, there has been no artificial kidney that is implantable in the body to provide any of the functions normally provided by a healthy kidney. It is to such artificial kidneys that the present invention is directed.
The above and other objects of this invention are achieved, in whole or in part, by a continuous internal peritoneal dialysis prosthesis and method employing an abdominal sac including a dialysate therein, said abdominal sac being adapted to be retained in the abdominal region of a person""s body for receiving unconcentrated urine through the walls of the sac without permitting dialysate to exit from the sac through the walls. The abdominal sac communicates the unconcentrated urine through a section of the patient""s bowel via a conduit that extends through the section of bowel. A region of the conduit within the section of the patient""s bowel includes apertures therein for communicating the unconcentrated urine in the conduit with walls of the section of bowel; thereby employing the natural function of the bowel to concentrate the urine. The prosthesis also includes a connector that is adopted for directing concentrated urine from the bowel to the urinary bladder.
In one preferred prosthesis of this invention, the conduit includes a first conduit section and a second conduit section. The first section communicates the abdominal sac with a pouch adopted to be placed in the thoracic region of the patient""s body. The second conduit section communicates with the pouch and extends through the section of the patient""s bowel. The second conduit section includes apertures for controlling the rate of flow of unconcentrated urine through the bowel so as to provide adequate time for the bowel to provide its required urine concentrating function, and to direct said concentrated urine to the urinary bladder for ultimate excretion by the body.
In the most preferred embodiment of this invention, the distal end of the second conduit communicates with the dialysis sac.
In the most preferred embodiment of this invention, the connecting means to the urinary bladder includes the right ureter connecting the bowel to the urinary bladder and most preferably, the connecting means is through the appendix or cecum.
The continuous internal peritoneal dialysis method of this invention includes the steps of providing an abdominal sac in the peritoneal region of a patient, said sac including a dialysate therein and a wall adopted for permitting unconcentrated urine to pass therethrough into the dialysate in the sac while preventing the escape of dialysate from the sac; directing the unconcentrated urine therein out of the abdominal sac and through a section of a patient""s bowel in which the urine is concentrated, and then directing the concentrated urine into the urinary bladder for subsequent excretion from the human body in a conventional, or normal manner.
In accordance with the preferred method of this invention, a portion of the urine that is not concentrated within the bowel is caused to flow back to the abdominal sac.
In the most preferred method of this invention, the step of directing the unconcentrated urine through the section of bowel is carried out by first directing the unconcentrated urine into a thoracic pouch located in the thoracic region of a patient, the abdominal sac and thoracic pouch being flexible.
Most preferably, the process employs the normal breathing activity of the patient to continuously direct the unconcentrated urine from the abdominal sac to the thoracic pouch and then through the section of bowel.
In another preferred embodiment, a prosthesis for continuous internal peritoneal dialysis comprises a thoracic pouch and first and second conduits. The first conduit communications unconcentrated urine and dialysate from the abdominal region of a patient""s body through the patient""s diaphragm to the thoracic region of the body. The thoracic pouch is adapted to be retained in the thoracic region of the patient""s body, and communicates with the first conduit to receive the unconcentrated urine and dialysate from the abdominal region. The second conduit extends from the thoracic pouch through the patient""s diaphragm and a section of the patient""s bowel. The second conduit communicates the unconcentrated urine and dialysate from the thoracic pouch with walls of the section of the bowel for concentrating the urine within the section of bowel. The section of bowel includes an exit port for directing the concentrated urine from the section of bowel to the urinary bladder of the patient.
In another preferred embodiment, an abdominal sac for internal peritoneal dialysis includes a semi-permeable membrane wall and is arranged for having a dialysate therein. The sac is adapted to be retained in the abdominal region of a patient""s body for receiving unconcentrated urine through the semi-permeable membrane wall without permitting the diaysate to exit from the abdominal sac through the wall. The dialysate asserts a chemical potential to draw in the unconcentrated urine by osmotic pressure through the semi-permeable membrane wall. The sac includes an extension expanding into a section of the patient""s bowel. The extension includes the semi-permeable membrane wall for permitting the received unconcentrated urine to exit into the section of bowel for concentrating the urine. The section of bowel includes an exit port for directing the concentrated urine from the section of bowel into the urinary bladder of the patient.
Further scope of applicability of the present invention will become apparent from the description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since the invention will become apparent to those skilled in the art from this detailed description.